June 17, 2010 -- A new emergency contraceptive fully effective for five days after sex should be approved by the FDA, the federal agency's expert advisory panel says.

By 11-0 votes, the panel found Ella to be safe and effective.

The drug, to be called Ella in the U.S., already is approved in Europe and sold there as EllaOne.

Currently, the only other approved emergency contraceptive is Plan B. Although Ella likely will be available only by prescription, Plan B is approved for over-the-counter sale to women aged 17 and older. Women younger than age 17 must have a prescription.

The two emergency contraceptives work differently:

Plan B contains levonorgestrel, a progestin hormone used in lower doses in many birth control pills.

Ella contains ulipristal, a non-hormonal drug that blocks the effects of key hormones necessary for conception.

Plan B should be taken as soon as possible after sex. It may work for up to 72 hours, but is ineffective once the hormonal surge that leads to ovulation occurs.

Although emergency contraception should not be delayed, Ella's efficacy does not fade for 120 hours (five days) after sex, regardless of whether the hormonal surge has occurred.

One possibly serious drawback to Ella is that it may be less effective in obese women. In a 6-5 vote, the panel said no specific labeling should be required to address this issue.

Can Ella Cause Abortion?

Ella belongs to a class of drugs called selective progesterone receptor modulators. The only other approved drug in this class is mifepristone, better known as RU-486. Mifepristone is approved for use as part of a regimen that induces abortion.

Because it is better absorbed by the body than mifepristone, Ella can be used at low doses that prevent conception but that should not cause abortion.

By a unanimous vote, the panel said there was no need for Ella to carry specific labeling warning against off-label use -- the use of a drug for a purpose other than the one for which it was approved. Nor was there a need for the manufacturer to conduct specific physician education on the issue.

It remains unclear whether Ella might increase the rate of spontaneous abortion in the few women who become pregnant despite using the drug.

Among women trying to become pregnant (and thus not taking emergency contraceptives), about 15% have a spontaneous abortion during the first trimester.

In clinical trials of Ella, 110 women who took the emergency contraceptive -- about 2% of study subjects -- became pregnant. As might be expected, 15% had spontaneous abortions. Another 66% had elective abortions, but for 12% of the women pregnancy results are not known.

"The actual spontaneous abortion rate could have ranged between 14% (assuming that none of these 11 pregnancies resulted in spontaneous abortion) to 27% (assuming all of these 11 pregnancies resulted in a spontaneous abortion)," FDA staff noted in a briefing document presented to the panel.

Nevertheless, the panel strongly recommended against requiring women to undergo a pregnancy test before taking Ella.

In Europe, HRA Pharma has established a post-approval study to gather information on pregnancy outcomes for women who take the drug. The panel recommended that the FDA make extension of this program to U.S. women a condition of approval.

Although the FDA is not required to follow the advice of its advisory panels, the favorable report submitted to the panel by FDA staff suggests that the agency will follow the panel's advice.